Israeli troops fired from close range early today on a four-car convoy carrying top Palestinian security officials who had just returned from talks with Israel on how to reduce friction after six months of fighting. Mohammed Dahlan, one of the three security chiefs, said Israel tried to assassinate him and his colleagues with heavy machine gun fire. His car was struck by seven bullets, and a bag with personal belongings that had rested near his feet in the car was also hit. Three of his bodyguards were hurt, including one who was shot in the leg and two who suffered broken limbs when one of the four cars overturned. Dahlan said no progress was made in security talks.